Instrument for measuring variable forces



Nov. 26, 1929. J. G. PAULIN 1,737,331

INSTRUMENT FOR MEASURING VARIABLE FORCES Filed Nov. 10, 192'! INVENTG Q Patented Nov. 26, 1929 UNETED STATES JOSUA GABRIEL PAULIN, OF STOCKHOLM, SWEDEN INSTRUMENT FOR MEASURING VARIABLE FORCES Application filed November 10, 1927, Serial No. 232,429, and in Sweden November 22, 1926.

The present invention refers to such instruments for measuring of variable forces in which the movable measuring member is actuated by the varying forces to be measured 5 on the one hand and by a counteracting spring 15 for measuring gas pressure, in which instrument the counteracting spring system consists of a single helical spring adapted to be regulated. Figures 2 and 3 show a front View and an elevation respectively of an embodiment of the invention adapted for the same purose. P In both of the instrument-s shown, the measuring member consists of an evacuated diaphragm box 2 secured to a frame plate 1, sald box being of the type generally used in aneroid barometers, the same being actuated by the external gas pressure, for instance the at-f mospheric pressure, on the one side, and by the counteracting spring system onthe other side. The movements of the diaphragm are transmitted to the spindle 8 of the pointer by' a system of strings, bands or equivalent flexible members serving as a gearing dev ce, the said system consisting in known manner of two bands or strings 5 connected each with one end of a transversal pin 4 on the pointer spindle, and of two bands or strings 6 con nected at their middle points with the strings 5, the upper ends of said bands or strings 6 being attached in the frame while their lower ends are attached each at one of two arms eX- tending from the diaphragm, said arms being denoted by 7 in Figure 1, and by 7 in nigures 2, 3. The pointer is spring actuated in such a manner that the band system is stretched, the strings 5 being thus bent angularly. The pointer spindle 8, which is pivotally arranged in a suitable manner, carries the pointer 8, the free end of which plays over a small zeroizing scale attached to the frame as at 9.

. In the known arrangement according to V Figure 1, the'spring system acting on the diaphragm and intended to balance the atmospheric pressure consists of a strong helical spring 10, the lower end of which is attached to a yoke-shaped part 11 connected with the diaphragm and carrying the arms 7, while the upper end of said helical spring is connected with a nut 13 threaded onto a micrometer screw 12; The micrometer screw is provided at its upper end with a turning knob 14. The nut 13 is provided with a laterally projecting arm 15, the forked outer end of which embraces a post 16 in the frame, said post serving as a guide, so that the nut will be raised or lowered, on rotation of the micrometer screw, without taking part in the rotary movement, the said nut thus increasing or decreasing the tension of the spring. Inasmuch as a very strong spring must be used to balance the entire air pressure acting on the diaphragm and as, moreover, this spring must be very severely tempered in order. to avoid subsequent elastic actions, great practical difficulties are met with in arranging suitable attachments for the spring at the diaphragm or the nut respectively. In regard to the severe tempering of the spring and also with respect to the central arrangement of the zeroizing mechanism it is not possible to bend the ends of the spring so that thepoints of attachment will be situated on the axis of the spring. Instead, the ends must be bent axially direct from the circum- 'ferences of the two outermost coil windings,

According to the present invention, these balancing the atmospheric pressure being composed, first, of a leaf-spring having a constant tension practically independent of the zeroizing device, said tension being adapted to balance per se approximately the atmospheric pressure, and, second, of one or more springs adapted to be controlled by means of the zeroizing device, it being; PCS. sible to select the tension of said springs compara-tively low, as it only represents the difference between the atmospheric pressure act= ing on the diaphragmfland the. constanttension of the leaf-spring. A leaf-spring may be tempered without difficulty to a very much higher degree of tempering than a spiral spring, vwhich latteriis'apt to cast or warp on severe tempering. The attachment box is secured to the lower side of the frame plate 1.. Attached by'means of a nut 17 against the downwardl directed diaphragm of the diaphragm box is the one shank of a yoke-shaped leaf spring 18, the upper shank of which is clamped alongits front edge into an interstice 1'9 providedin a'bar 20. This latter bears onthe upper side against two stop screws 21, the points of which engage;

corresponding rece$esin the bar, and is provided with a forwardly projecting arm- 22, the'yoke-sh'aped' end of which is'engaged with tlje head'of a-screw' 23 threaded into the frame ate. i vh-ich is greater than the atmospheric pres sure acting on the diaphragm, may be ad; justed to a certain extent by means of the screws 21 and 23.

On both sides of the pointof attachment 7 at the diaphragm, the 'leaf spring. is provided withlaterally'projecting laps 24 form ing attachments for the lower ends of each of twoxhelical' springs 26, the upper ends of which are secured to a yoke 25" rigidly connected with a nut-1'3 adapted to be adjusted vertically in the same way as the corresponding nut. in Figure L The micrometer screw 12 engaging the nut is journalledatits lower end in a fixed journal bearing 27 The'pa-rts 10 to 14 together" form a zeroizing device for restoring the diaphragm to a certain normal position with the aid. of the indications of the zero pointer 8; The zeroizing' device,

the adjustment of which maybe read off on a-fiXed scale by means of a pointer 28 attached to the micrometer screw,serves to regulate the tensions of the comparatively weak heli- The tension ofthe leaf-spring 18,

cal springs 26, whereas the tension of the leaf-sprin r 18 is independent of the zeroizing device. he said reading scale preferably occupies the major portion 9 of a circular disk provided on the upper side of the frame, whereas the rest of the circumference of this disk is occupiedby the zeroizing scale 9.

In'the embodiment of the invention as illustrated, the controllable helical springs 26 obviously counteract the constant loaf-spring 18," the tensionof whichshould in this case be greater than the occurring atmospheric pressures. Evidently, the arrangement may instead be sodevised that the controllable springs act in the same direction as the constant leaf-spring, in: whichv case the tension ofthelatter obviously should be smaller than theoccurring. air pressures.

Thelower shank of the leaf-spring18is provided with an angularly bent extension.

18 forming a tongue 30 between two stop screws 29, said tongue l111'l1l31ng.tl1(-3'Il1OV6= ments of the diaphragm, and also forming;

thetwo lateral projections or-arms 7, which form the movabie oints. ofattachment for the systemof ban s or strings5, 6, .constituting, in a manner already'd'escribedin connection with Figure 1, a gearin'g device inserted between the diaphragm; and the pointer spindle The latteris suspended between two fixed supports 31by means othelical springs 32 tending to turn the pointer spindle 111 a certain direction of rotation. Through this elastic suspension of the zero pointer 8' the frictional resistances and the play occurring in ordinary pivotal mounting devices are eliminated. As, in addition, the gearing device formed by the" soft and fiexi'blebands or strings-:5, 6also' operates practically frictionless and without play, the movable sys; tem of the'instrum'ent possesses a-very high degree of easy movement, which makes it possible to select a great ratio of gear and to secure averyhigh degree of sensibility.

When the tension of the helical springs 26' is-so adapted that the resulting spring force of tl i'e di-aphra'gm accurately balances the atmospheric pressure, the pointer 8 occupies its middle position and points at the zero line of thezero scale 9. If the atmospheric pressure decreases; the diaphragm will be bulged downwardly by reason of the. excess tensionof the leaf-spring 18, the obtuse angles of-the bands 6 being somewhat'increased, the'z'ero pointer 8 being then deflected to the left (Figure 2). In order now to restore the diaphragm toith'e normal position for the purpose of reading off the instrument, the zeroiz ing knob-.14 is obviously to be turned in a clockwise direction, until. the pointer again points at zero. By this turning movement,

the nut 13 and .the yoke 25'will' be raised,

whereby the tension of'the helical springs 26 is increased, the resulting spring; tension of the diaphragm being consequently reduced into agreement with the reduced air pressure. On a rising air pressure, the compensation takes place reversely by turning the knob 14 in the opposite direction, whereby the tension of the helical springs is reduced and the total spring tension on the diaphragm is increased.

The total turning movement of the zeroizing knob 14 at the moment at which the pointer 8 is adjusted at zero, obviously'constitutes a measure of the air pressure prevailing for the time being, which pressure may thus be read off directly by means of the pointer 28 on the scale pertaining thereto.

I claim: 1

1. An instrument for measuring variable forces comprising in combination a measuring member movable under the influence of said forces, a yoke-shaped leaf-spring connected with the measuring member so as to counter-act the variable forces, a helical spring system cooperating with said leaf spring, means for varying the tension of said helical spring system so as to balance the force to be measured by the resultant spring tension acting on the measuring member.

2. An instrument as claimed in claim 1, characterized by the helical spring system consisting of a number of springs arranged symmetrically with respect to the middle plane of the leaf spring.

3. An instrument for measuring variable forces comprising in combination a measuring member movable under the influence of said forces, a yoke-shaped leaf-spring connected with the measuring member so as to counter-act the variable forces, a displaceable fixture provided in the frame of the instrument, a helical spring system inserted between the said fixture and the measuring member and means for adjusting said fixture so as to vary the tension of the helical spring system.

4. In an aneroid-barometer in combination, a yoke-shaped leaf-spring connecting the diaphragm with the frame, a displaceable fixture in the frame, a helical spring system inserted between said fixture and the diaphragm, and means for adjusting said fixture so as to vary the tension of the helical spring system.

5. An aneroid-barometer as claimed. in claim 4, characterized by the helical spring system being secured between the movable shank of the leaf-spring on the one side and a nut threaded onto a rotatable screw on the other side.

6. An instrument as claimed in claim 1, characterized by the fact that the movements of the measuring member are transmitted to the zero pointer through the medium of an extension of the movable shank ofthe leafspring, said shank thus forming a lever arm adapted to magnify the movement.

7. An instrument as claimed in claim 1, characterized by the fact that the movements of the measuring member are transmitted 8. An instrument as claimed in claim 1,

characterized by the pointer being suspended by means of elastic suspension members. In testimony whereof I affix my signature.

J OSUA GABRIEL PAULIN. 

